If Sinister can get his helmet off (or gets one of his lackeys to do it), then he could pretty easily jumble Juggernaut's brain from there.
EI
Eternal IdolLono, "The Dog"
I agree that if Sinister could remove Juggernaut's helmet, he win via telepathy. However, I'm not sure if he's physically or telekinetically able to remove the helmet in the first place.
WP
Wei PhoenixOne-Eyed Dragon Of Oshu
Yeah if Sinister could then he would win but he can't get it off.
KIN
KingD19Shai-Gen's Enigmatic Wong
The fight would more than likely be a tie, Jugg's can't permanently hurt Sinister, and Sinister can't get in Jugg's head.